Ajax Push - what to consider?

I'm looking into "Comet", "Ajax Push" or "Reverse Ajax" and have found APE: http://www.ape-project.org. It seems very promising. Any one with experience with this? Any pros and cons I should know about?

Also, are there any other engines I should be considering?

Sounds like you want to be using WebSockets or Comet.

If you want to self-host there are the following options:

• http://faye.jcoglan.com/
• http://socket.io/
• Jetty: http://blogs.webtide.com/gregw/entry/jetty_websocket_server
• http://code.google.com/p/pywebsocket/
• Ruby EventMachine WebSocket server: https://github.com/igrigorik/em-websocket
• Meteor: http://meteorserver.org/
• GlassFish: http://glassfish.java.net/
• ErlyComet: http://code.google.com/p/erlycomet/
• cometD: http://cometdproject.dojotoolkit.org/

If you don't want to host the real-time infrastructure then you could use a hosted service such as Pusher who I work for.